Hydroacoustics

Long term measurement of underwater noise with autonomous recorder in the North Sea and the Baltic
Customer: Federal Agency for Nature and Conservation and University of Veterinary Medicine Hannover Institute of Terrestrial and Aquatic Wildlife Research (ITAW)
Objective: To measure ambient noise from anthropogenic and natural sources in German environmental protected areas. Those measurements were intended to document the acoustic impact on marine life before, during and after construction of different offshore wind parks. These measurements were enclosed in the project “Cluster 7: Effects of underwater noise on marine mammals”.
Scope:
  • 5 measurement campaigns since 2012
  • 40 measurement positions
  • Mean measurement periods: 3 months continuous recording of spectral sound data
  • Data processing and evaluation
  • Development of sound filters for automatic noise source classification
Link: "Cluster project: Impact of underwater noise on marine vertebrates" (pdf-download)

Masking effects of airguns imposed on marine mammals
Customer: German Federal Environment Agency
Objective: To assess the masking effect on marine mammal communication induced by seismic exploration with airguns.
Scope: Interpretation and evaluation of underwater sound data, Calculation of airgun noise propagation over long distances, prediction of received sound spectra, comparison with communication signals of marine mammels.
Link: "Assessment of potential for masking in marine mammals of the Antarctic exposed to underwater sound from airguns"

Development of a noise map for the German North- and Baltic Sea
In cooperation with the Curtain University (Australia), DW-ShipConsult developed a program to display noise distribution in German waters. The SEANAT (SEA Noise Analysis Tool) program enables the user to investigate underwater acoustic problems and predict the received underwater noise level at a specific location. SEANAT allows calculations for single and multiple sources and covers a frequency range from 31.5 Hz to 16 kHz. The visual features provide the possibility to show a noise map of a selected region as a function of different sources and environmental conditions.
Link: SEANAT

Reducing sound radiation from piles
In cooperation with MENCK, DW-ShipConsult developed a concept on how to arrange slots in piles in order to reduce the emitted noise during piledriving operation. This technology supports the different ambitions to reduce underwater noise and comply with the requirements of the German BSH on underwater noise levels.
Link: Reducing sound radiation

Underwater noise measurements of ships
DW-ShipConsult has executed a variety of different underwater radiated noise measurements in order to determine the source level of ships. Customers of these projects are the shipowners of the vessels. In these measurement campaigns, underwater sound data was retrieved and evaluated of:

  • A Bulk Carrier during cargo operations in port in order to assess the environmental impact
  • A cruise vessel during transit in the North Sea in order to assess its environmental impact and to gain input data for an acoustic ship model
  • Different container vessels during transit in the English Channel and the Baltic Sea in order to gain input data for an acoustic ship model and to verify the effectivity of a propeller modification
  • Different special vessels which may not be named for confidentiality reasons in order to assess their detectability

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